Validation of Modaplex POLE mutation assay in endometrial carcinoma

The TCGA-based molecular classification of endometrial cancer has emerged as an important tool to stratify patients according to prognosis. A simplified scheme has been proposed, by using immunohistochemistry for p53, MSH6, and PMS2 and a molecular test for POLE mutations (NGS or Sanger sequencing, techniques that are not available in many centers worldwide). In this study, we validate a novel method that allows simultaneous analysis of multiple pathogenic POLE mutations. The Modaplex technology integrates polymerase chain reaction and capillary electrophoresis. The design of this study encompassed 4 different steps: (1) a retrospective-pilot phase, with 80 tumors, balancing the four molecular subgroups. (2) A retrospective phase of 25 tumors obtained between 2016 and 2020, and 30 tumors obtained between 2000 and 2015. (3) An inter-laboratory corssavalidation step with 19 cases (belonging to phases 1 and 2). (4) A prospective cohort of 123 tumors, of unknown POLE status, with simultaneous validation by Sanger sequencing. A total of 258 samples were analyzed. In the first and second phases, the test showed positive/negative predictive values of 100%, by correctly identifying POLE mutation status in 79/79 and 55/55 cases. Phase 3 showed 100% of inter-laboratory consistency. Phase 4 showed 16 positive samples out of the 123 prospective cases. Overall, the test has revealed sensitivity and specificity of 100%, identifying a total of 47 POLE-mutated tumors. We have shown that this technique allows faster and easier identification of multiple pathogenic POLE mutations with high robustness and confidence when comparing to other tests such as Sanger sequencing.